Datasheet

Operating modes M41ST85W
18/43 Doc ID 7531 Rev 11
If data retention lifetime is a critical parameter for the system, it is important to review the
data retention current specifications for the particular SRAMs being evaluated. Most SRAMs
specify a data retention current at 3.0 volts. Manufacturers generally specify a typical
condition for room temperature along with a worst case condition (generally at elevated
temperatures). The system level requirements will determine the choice of which value to
use. The data retention current value of the SRAMs can then be added to the I
BAT
value of
the M41ST85W to determine the total current requirements for data retention. The available
battery capacity for the SNAPHAT
®
top of your choice can then be divided by this current to
determine the amount of data retention available (see Table 21 on page 40).
For a further more detailed review of lifetime calculations, please see application note
AN1012.